Data communication networks may include various computers, servers, nodes, routers, switches, hubs, proxies, and other devices coupled to and configured to pass data to one another. These devices are referred to herein as “network elements,” and may provide a variety of network resources on a network. Data is communicated through data communication networks by passing protocol data units (such as packets, cells, frames, or segments) between the network elements over communication links on the network. A particular protocol data unit may be handled by multiple network elements and cross multiple communication links as it travels between its source and its destination over the network. Hosts such as computers, telephones, cellular telephones, Personal Digital Assistants, and other types of consumer electronics connect to and transmit/receive data over the communication network and, hence, are users of the communication services offered by the communication network.
Network elements are typically implemented to have a control plane that controls operation of the network element and a data plane that handles traffic flowing through the network. The data plane typically will have a collection of line cards having ports that connect to links on the network. Data is received at a particular port, switched within the data plane, and output at one or more other ports onto other links on the network. To enable the data to be handled quickly, the data plane is typically implemented in hardware so that all of the decisions as to how to handle the data are performed using hardware lookups, etc.
The packets are transferred across the network in accordance with a particular protocol, such as the Internet protocol (IP). Internet Protocol version 4 (IPv4) is the fourth revision in the development of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet. IPv4 is still by far the most widely deployed Internet Layer protocol.
IPv4 is a connectionless protocol for use on packet-switched Link Layer networks (e.g., Ethernet). It operates on a best effort delivery model, in that it does not guarantee delivery, nor does it assure proper sequencing, or avoid duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol (e.g., Transmission Control Protocol).
IPv6 (Internet Protocol Version 6) is a set of specifications from the Internet Engineering Task Force (IETF) that are an upgrade of IP Version 4 (IPv4). The basics of IPv6 are similar to those of IPv4—devices can use IPv6 as source and destination addresses to pass packets over a network, and tools like ping work for network testing as they do in IPv4, with some slight variations.
One improvement in IPv6 over IPv4 is that IP addresses are lengthened from 32 bits to 128 bits. This extension anticipates considerable future growth of the Internet and provides relief for what was perceived as an impending shortage of network addresses. IPv6 also supports auto-configuration to help correct most of the shortcomings in version 4, and it has integrated security and mobility features.
Additional IPv6 features include support of source and destination addresses that are 128 bits (16 bytes) long, the use of Multicast Neighbor Solicitation messages to resolve IP addresses to link-layer addresses, the use of Multicast Listener Discovery (MLD) messages to manage membership in local subnet groups, and the use of ICMPv6 Router Solicitation and Router Advertisement messages to determine the IP address of the best default gateway.
Network devices may use MultiLink Trunks (MLTs) to communicate with each other. MLT is a method of link aggregation that allows multiple point-to-point links to be aggregated together in order to provide a single logical trunk. An MLT provides the combined bandwidth of the multiple links, as well as the physical layer protection against failure of any single link. Split MultiLink Trunk (SMLT) is MLT with one end of which is split between at least two aggregation devices.
Existing SMLT solution provides redundancy and fast failover at Layer 2 only—the peers exchange their Media Access Control (MAC) addresses but not their IPv6 addresses. The Virtual Router Redundancy Protocol (VRRP)v3 protocol uses a different mechanism for providing redundancy. VRRPv3 utilizes periodic advertisements that allow multiple routers to elect the single master which instantiates the redundant IPv6 and MAC addresses. Failover is achieved by electing a new master in situations when a certain number of advertisements fail to be received by the backup routers.